A downhole drilling assembly is typically connected to a lower end of a drill string in order to conduct drilling operations in a borehole. A downhole drilling assembly may be comprised of equipment including, but not limited to, drill collars, stabilizers, reamers, sensors, LWD/MWD communication systems, and/or one or more drilling apparatus.
A drilling apparatus in a downhole drilling assembly may be comprised of apparatus including, but not limited to, a downhole drilling motor, a rotary steerable tool, a steering tool, or a combination of such apparatus. A drill bit is typically included at a lower end of the drilling apparatus. A bearing pack typically transmits forces between the drill bit and a housing of the drilling apparatus.
It is widely accepted that a drilling apparatus that is as short as possible may provide many potential advantages, particularly when the drilling apparatus includes a bend and is used for directional drilling. Drilling holes with a higher rate of curvature, extending bearing life and improving toolface control are among some of the potential benefits of a relatively short drilling apparatus. Drilling in rotary mode with a drilling apparatus including a bend may also be possible with larger bend angles if the drilling apparatus is relatively short.